Will a retro fit hyd roller cam work in an oe roller block? and vice versa?

Im going to build a 406 and it will have a hyd roller cam but for now I want to buy the cam for it and use it in my current 355(OE Roller) because the current cam is too tight for my comp ratio and it detonates like an SOB.

Yes but it does take some messing around.

An old roller or flat tappet can be used in an OEM roller block. The roller will require a cam button for retention. Both will use the old style gears to get the proper cam gear to block thrust face.

A new roller cam for OEM roller blocks can be used in older non roller blocks by making a thrust plate that fits between the block and the OEM roller cam's drive gear to take up the added length of the cam nose. This is easily accomplished by taking an OEM thrust plate and cutting its mounting ears off. The cam is then retained by a good old fashion cam button. You can either run aftermarket rollers or adapt the block to run 4.3 V6 roller tappets. These are shorter than the 5.0/5.7 tappet so they don't expose the oil flow relief at max lift with older engine's lower lifter blocks. A conventional OEM spider is used by drilling thru the main oil galley and tapping the upper and lower sections of the galley bore to accept a 5/16's course thread bolt. After test fitting the bolt installation, remove the the bolt's threads where it passes inside the oil galley to maximize oil flow around the bolt.